Effect of Drying Process on Pesticide Residues in Grapes

In this study, drying kinetics of chlorpyrifos, diazinon, dimethoate andmethidathion pesticides on grape samples were determined. Grapes were driedunder two conditions: by sunlight (for 21 days) and in a ventilated oven atdifferent temperatures (at 50 °C for 72 hrs, at 60 °C for 60 hrs, at 70 °C for48 hrs, at 80°C for 36 hrs). During sun drying, half-livesof chlorpyrifos,diazinon and methidathion were 5.64, 6.42 and 5.25 days,respectively. The data for dimethoate did not fit 0th,, 1stand 2nd order kinetics. During oven-drying, the pesticides followedthe first order kinetic model. When the temperature increased, degradation ofpesticides raised. The activation energies of dimethoate,diazinon, chlorpyrifos and methidathion were calculated as 42.02, 42.18, 42.01and 41.08 J/mol, respectively.